Preparation of azo colorants in microreactors and their use in electrophotographic toners and developers, powder coatings, ink jet inks and electronic medias

ABSTRACT

The invention is directed to an electrophotographic toner or developer, powder coating, ink jet ink or an electronic media having an azo colorant prepared by conducting the diazotization of aromatic or hetaromatic amines or the azo coupling reaction or the diazotization and the azo coupling reaction in a microreactor.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation in part of co-pending U.S.Ser. No. 09/780,218, filed Feb. 9, 2001, the entire disclosure of whichis incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to the field of azo colorants. Azocolorants are customarily produced in industry in batch operations inreaction vessels by mixing the starting materials together in aqueousphase (Fisher, Organische Chemie, Verlag Chemie, Weinheim/Bergstraβe,1965, p. 890 ff., 1431, 1796 ff.).

[0003] Another way is the continuous mixing of equivalent amounts of thestarting materials in the form of aqueous acidic or aqueous alkalinesolutions in, for example, mixing nozzles and continuous flow reactorswith or without a postreaction phase in a reaction vessel (azo coupling:DE 1 544 453, EP 244 686; diazotization: EP-A-0 006 190).

[0004] The principal process operations involved are the diazotizationof aromatic or hetaromatic amines and the azo coupling reaction. Certainazo pigments may subsequently require a metal exchange reaction (laking)and/or an aftertreatment in water/solvents to obtain the desired crystalproperties. In the case of some azo dyes, a reaction is subsequentlycarried out to form metal complexes.

[0005] In all these processes, it is essential that the processparameters, such as temperature, time and (in the case of azo pigments)also in particular the degree of mixing, be controlled, if the productsare to be pure and of high and consistent quality. One problem withthese processes is the scaleup of new products from the laboratory scaleto the large industrial scale.

[0006] It is an object of the present invention to provide a process forpreparing azo colorants that provides optimal control of the processparameters, ensures improved mixing of the reactants and simplifiesscaleup.

[0007] It is a further object of the present invention to provide azocolorants having improved coloristic properties for use inelectrophotographic toners and developers, powder coatings, ink jet inksand electronic medias.

[0008] DD 246 257 A1 discloses the possibility of using miniaturizedapparatuses for chemical reactions where the chemical entities to betreated are only available in small quantities or are very costly, sothat large dead spaces in the equipment become unaffordable. DE 3 926466 C2 describes strong exothermic chemical reactions of two chemicalentities in a microreactor.

[0009] Microreactors for chemical reactions are constructed from stacksof grooved plates and are described in DE 39 26 466 C2 and U.S. Pat. No.5,534,328. It is pointed out in U.S. Pat. No. 5,811,062 thatmicrochannel reactors are preferably used for reactions that do notrequire or produce materials or solids that would clog themicrochannels.

SUMMARY OF THE INVENTION

[0010] It has now been found that, surprisingly, microreactors areuseful for carrying out diazotization and azo coupling and also metalexchange reactions or metal complexing reactions to prepare azocolorants, such as azo pigments and azo dyes.

DESCRIPTION OF THE DRAWINGS

[0011] The invention will become more fully understood by reference tothe following detailed description of the invention and the appendeddrawings in which:

[0012]FIG. 1 is a perspective view of the compact parts that form themicroreactor.

[0013]FIG. 2 is a schematic of the apparatus used in the process.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] As used herein, microreactor comprehends micro- and minireactors,which differ only by reason of the dimensions and construction of thereaction channel structures.

[0015] It is possible to use, for example, microreactors as known fromthe cited references or from publications of the Institut fürMikrotechnik Mainz GmbH, Germany, or else commercially availablemicroreactors, for example Selecto™ (based on Cytos™) from CellularProcess Chemistry GmbH, Frankfurt/Main.

[0016] The invention accordingly provides a process for preparing azocolorants by conducting the diazotization of aromatic or hetaromaticamines or the azo coupling reaction or the metal exchange reactions orthe metal complexing reactions or the diazotization and the azo couplingreaction and the metal exchange or metal complexing reactions in amicroreactor.

[0017] Advantageously, the preferably aqueous solutions or suspensionsof the starting materials are fed to the microreactor continuously andpreferably in equivalent amounts. The classic process assistants such asresins, surfactants and other additives may likewise be used in theprocess of the invention.

[0018] The starting materials for the diazotization reaction arearomatic or hetaromatic amines or their ammonium salts, for exampleaniline, 2-nitroaniline, methyl anthranilate, 2,5-dichloroaniline,2-methyl-4-chloroaniline, 2-chloroaniline,2-trifluoromethyl-4-chloroaniline, 2,4,5-trichloroaniline;3-amino-4-methylbenzamide, 2-methyl-5-chloroaniline,4-amino-3-chloro-N′-methylbenzamide, o-toluidine, o-dianisidine,2,2′,5,5′-tetrachlorobenzidine, 2-amino-5-metiiylbenzenesulfonic acid,2-amino-4-chloro-5-methylbenzenesulfonic acid.

[0019] Of particular interest for azo pigments are the following aminecomponents:

[0020] 4-methyl-2-nitrophenylamine, 4-chloro-2-nitrophenylamine,3,3′-dichlorobiphenyl-4,4′-diamine, 3,3′-dimethylbiphenyl-4,4′-diamine,4-methoxy-2-nitrophenylamine, 2-methoxy-4-nitrophenylamine,4-amino-2,5-dimethoxy-N-phenylbenzenesulfonamide, dimethyl5-aminoisophthalate, anthranilic acid, 2-trifluoromethylphenylamine,dimethyl 2-aminoterephthalate, 1,2-bis(2-aminophenoxy)ethane,diisopropyl 2-aminoterephthalate,2-amino-4-chloro-5-methylbenzenesulfonic acid, 2-methoxyphenylamine,4-(4-aminobenzoylamino)benzamide, 2,4-dinitrophenyl-amine,3-amino-4-methylbenzamide, 3-amino-4-chlorobenzamide,3-amino-4-chlorobenzoic acid, 4-nitrophenylamine,2,5-dichlorophenylamine, 4-methyl-2-nitrophenylamine,2-chloro-4-nitrophenylamine, 2-methyl-5-nitrophenylamine,2-methyl-4-nitrophenylamine, 2-methyl-5-nitrophenylamine,2-amino-4-chloro-5-methylbenzenesulfonic acid,2-aminonaphthalene-1-sulfonic acid,2-amino-5-chloro-4-methylbenzenesulfonic acid,2-amino-5-chloro-4-methylbenzenesulfon ic acid,2-amino-5-methylbenzenesulfonic acid, 2,4,5-trichlorophenylamine,3-amino-4-methoxy-N-phenylbenzamide, 4-aminobenzamide, methyl2-aminobenzoate, 4-amino-5-methoxy-2,N-dimethylbenzenesulfonamide,monomethyl 2-amino-N-(2,5-dichlorophenyl)terephthalate, butyl2-aminobenzoate, 2-chloro-5-trifluoromethylphenylamine,4-(3-amino-4-methylbenzoylamino)benzenesulfonic acid,4-amino-2,5-dichloro-N-methylbenzenesulfonamide,4-amino-2,5-dichloro-N,N-dimethyl-benzenesulfonamide,6-amino-1H-quinazolin-2,4-dione,4-(3-amino-4-methoxy-benzoylamino)benzamide,4-amino-2,5-dimethoxy-N-methylbenzenesulfonamide,5-aminobenzimidazolone,6-amino-7-methoxy-1,4-dihydroquinoxalin-2,3-dione, 2-chloroethyl3-amino-4-methylbenzoate, isopropyl 3-amino-4-chlorobenzoate,3-amino-4-chlorobenzotrifluoride, n-propyl 3-amino-4-methylbenzoate,2-aminonaphthalene-3,6,8-trisulfonic acid,2-aminonaphthalene-4,6,8-trisulfonic acid,2-aminonaphthalene-4,8-disulfonic acid,2-aminonaphthalene-6,8-disulfonic acid,2-amino-8-hydroxynaphthalene-6-sulfonic acid,1-amino-8-hydroxy-naphthalene-3,6-disulfonic acid,1-amino-2-hydroxybenzene-5-sulfonic acid,1-amino-4-acetylaminobenzene-2-sulfonic acid, 2-aminoanisole,2-aminomethoxybenzene-ω-methanesulfonic acid, 2-aminophenol-4-sulfonicacid, o-anisidine-5-sulfonic acid,2-(3-amino-1,4-dimethoxybenzenesulfonyl)ethyl sulfate and2-(1-methyl-3-amino-4-methoxybenzenesulfonyl)ethyl sulfate.

[0021] The following amine components are of particular interest for azodyes:

[0022] 2-(4-aminobenzenesulfonyl)ethyl sulfate,2-(4-amino-5-methoxy-2-methylbenzene-sulfonyl)ethyl sulfate,2-(4-amino-2,5-dimethoxybenzenesulfonyl)ethyl sulfate,2-[4-(5-hydroxy-3-methylpyrazol-1-yl)benzenesulfonyl]ethyl sulfate,2-(3-amino-4-methoxybenzenesulfonyl)ethyl sulfate,2-(3-aminobenzenesulfonyl)ethyl sulfate. The amine to be diazotized, orits ammonium salt, preferably its hydrochloride or sulfate, ispreferably dissolved or suspended in water and/or an organic solvent andthe resulting solution or suspension is continuously introduced into themicroreactor (reactant stream A).

[0023] Concurrently, a solution or suspension, preferably an aqueoussolution or suspension, of a diazotizing agent, preferably NaNO₂ ornitrosylsulfuric acid, is continuously introduced into the microreactor(reactant stream B). In the reactor, reactant streams A and B arecontinuously mixed with each other and reacted.

[0024] The starting materials for azo coupling reactions are diazoniumsalts, for example as above-mentioned or -prepared, and couplingcomponents in solution or suspension.

[0025] The following coupling components are of particular interest forazo pigments:

[0026] acetoacetarylides

[0027] and R_(k)═CH₃, OCH₃, OC₂H₅, NO₂, Cl, NHCOCH₃ and n=0 to 3; andalso R₂═H, CH₃ and C₂H₅,

[0028] bisacetoacetylated diaminobenzenes and -biphenyls,N,N′-bis(3-hydroxy-2-naphthoyl)phenylenediamines (each optionallysubstituted), and also pyrazolones

[0029] The following coupling components are of particular interest forazo dyes:

[0030] 4-[5-hydroxy-3-methylpyrazol-1-yl]benzenesulfonic acid,2-aminonaphthalene-1,2-disulfonic acid,5-methoxy-2-methyl4-[3-oxobutyrylamino]benzenesulfonic acid,2-methoxy-5-methyl-4-[3-oxobutyrylamino]benzenesulfonic acid,4-acetylamino-2-aminobenzenesulfonic acid,4-[4-chloro-6-(3-sulfophenylamino)-[1,3,5]-triazin-2-yl-amino]-5-hydroxynaphthalene-2,7-disulfonicacid, 4-acetylamino-5-hydroxynaphthalene-2,7-disulfonic acid,4-amino-5-hydroxynaphthalene-2,7-disulfonic acid, 5-hydroxy-1-[4-sulfophenyl]-1H-pyrazole-3-carboxylic acid,2-aminonaphthalene-6,8-disulfonic acid,2-amino-8-hydroxynaphthalene-6-sulfonic acid,1-amino-8-hydroxynaphthalene-3,6-disulfonic acid, 2-aminoanisole,2-aminomethoxybenzene-ω-methanesulfonic acid and1,3,5-trishydroxybenzene.

[0031] The azo coupling is preferably carried out in aqueous solution,but it is also possible to use organic solvents, if appropriate mixedwith water, for example aromatic hydrocarbons, hydrochlorocarbons,glycol ethers, nitriles, esters, dimethylformamide, tetramethylurea andN-methylpyrrolidone.

[0032] To carry out the azo coupling reaction according to theinvention, a solution or suspension of the diazonium salt (reactantstream C) and a solution or suspension of the coupling component(reactant stream D) are continuously introduced into the microreactorand continuously mixed with each other therein and reacted.

[0033] The starting materials for laking are azo colorants that containacid groups, in the form of the free acids or their, for example, alkalimetal salts or salts of alkaline earth metals, ammonium salts oraluminum or manganese salts.

[0034] To lake azo pigments, a metal salt solution, for example anaqueous calcium, strontium bromine or manganese salt solution (reactantstream E), is mixed with the solution or suspension of an azo colorantthat contains acid groups (reactant stream F), and brought to atemperature between 30 and 100° C., in the microreactor. The lakingreaction takes place in the reactor itself or is initiated there. Thereaction may be completed in a downstream continuous tubular reactor(delay vessel).

[0035] For the purposes of the present invention, not only thediazotization, the azo coupling reaction but also the laking reaction orthe metal complexing reaction may each be carried out in (successive)microreactors, or the diazotization is carried out in a conventionalmanner and only the azo coupling reaction is carried out in themicroreactor, or the diazotization is carried in the microreactor andthe azo coupling is carried out in a conventional manner. Similarly, thelaking may in each case be carried out conventionally or else in amicroreactor. It is also possible to use microreactors having two ormore reaction zones for the individual reaction steps.

[0036] A microreactor is constructed from a plurality of laminae whichare stacked and bonded together and whose surfaces bearmicromechanically created structures which interact to form reactionspaces for chemical reactions. The system contains at least onecontinuous channel connected to the inlet and the outlet.

[0037] The flow rates of the material streams are limited by theapparatus, for example by the pressures which result depending on thegeometry of the microreactor. It is desirable for the reaction to takeplace completely in the microreactor, but it is also possible to adjoina delay zone to create a delay time that may be required.

[0038] The flow rates are advantageously between 0.05 and 5 I/min,preferably between 0.05 and 500 ml/min, particularly preferably between0.05 and 250 ml/min, especially between 0.1 and 100 ml/min.

[0039] A microreactor useful for preparing azo colorants is described inFIG. 1 by way of example.

[0040] The present microreaction system is constructed from sixmicrostructured metal laminae, stacked and bonded together, plus a lidplate (LP) and a base plate (BP) to form a processing module that isfirmly held or bonded together to compress sealing sheets between theplates.

[0041] The present microreaction system includes two heat exchangers forcooling and/or heating medium, a mixing zone for mixing the reactantsand a short delay zone.

[0042] The heat exchanger (W1) preheats the reactant streams flowingseparately into plate (E). The reactant streams are then mixed withinplates (M), which form a conjoint space. The delay zone (R) brings thereaction mixture to the desired reaction temperature with the aid of theheat exchanger (W2), so that the desired chemical reaction can takeplace.

[0043] The microreaction system is operated continuously, and the fluidquantities which are mixed with each other in each case are in themicroliter (μl) to milliliter (ml) region.

[0044] The dimensions of the microstructured regions within the reactorare decisive for preparing azo colorants in this microreaction system.These dimensions have to be sufficiently large that, in particular,solid particles can pass through without problem and so do not clog upthe channels. The smallest clear width of the microstructures should beabout ten times larger than the diameter of the largest pigmentparticles. Furthermore, it has to be ensured, by appropriate geometricstyling, that there are no dead water zones, for example dead ends orsharp corners, where for example pigment particles could sediment.Preference is therefore given to continuous paths having round corners.The structures have to be sufficiently small to exploit the intrinsicadvantages of microreaction technology, namely excellent heat control,laminar flow, diffuse mixing and low internal volume.

[0045] The clear width of the solution- or suspension-ducting channelsis advantageously 5 to 10 000 μm, preferably 5 to 2 000 μm, particularlypreferably 10 to 800 μm, especially 20 to 700 μm.

[0046] The clear width of the heat exchanger channels depends primarilyon the clear width of the liquid- or suspension-ducting channels and isadvantageously not more than 10 000 μm, preferably not more than 2 000μm, especially not more than 800 μm. The lower limit of the clear widthof the heat exchanger channels is uncritical and is at most constrainedby the pressure increase of the heat exchanger fluid to be pumped and bythe necessity for optimum heat supply or removal.

[0047] The dimensions of the microreaction system used are: Heatexchanger structures: channel width ˜600 μm channel height ˜250 μm Mixerand delay time: channel width ˜600 μm channel height ˜500 μm

[0048] The six superposed and closely conjoined metal laminae arepreferably supplied with all heat exchanger fluids and reactants fromabove. The product and the heat exchanger fluids are preferably likewiseremoved upwardly. The possible supply of third and fourth liquidsinvolved in the reaction (eg. buffer solutions) is realized via aT-junction located directly upstream of the reactor (FIG. 2), ie. onereactant can be premixed with the buffer solution. The requisiteconcentrations and flows are preferably controlled via precision pistonpumps and a computer-controlled control system. The reaction temperatureis monitored via integrated sensors and monitored and controlled withthe aid of the control system and of a thermostat/cryostat.

[0049] The preparation of mixtures of feedstocks to form materialstreams may also be carried out in advance in micromixers or in upstreammixing zones. It is also possible for feedstocks to be metered intodownstream mixing zones or into downstream micromixers or -reactors.

[0050] The system used here is made of stainless steel; other materials,for example glass, ceramic, silicon, plastics or other metals, may alsobe used.

[0051] Diazotizations are carried out at temperatures of −10 to +80° C.,preferably −5 to +30° C., and azo couplings at 0 to 90° C., preferablyat 10 to 60° C.

[0052] For both the diazotization and the azo coupling, the reactantstreams may be admixed with buffer solutions, preferably of organicacids and salts thereof, for example acetic acid/acetate buffer, citricacid/citrate buffer, or of inorganic acids and salts thereof, forexample phosphoric acid/phosphate or carbonic acid/carbonate.

[0053] The process of the invention provides high reaction rates withsignificantly higher reaction temperatures than, for example, in thebatch process. More particularly, temperature-sensitive reactants, forexample diazonium salts and alkaline solutions of2-hydroxy-3-naphtharylides, can be reacted with advantage. The high heattransfer rate during the short residence time in the micro- orminireactor makes it possible to realize a short thermal stress of thereactant within a narrowly definable time window.

[0054] The process of the invention provides azo colorants, such as azopigments and azo dyes.

[0055] Azo pigments may be monoazo or disazo (laked and unlaked)pigments. It is also possible to prepare mixtures of azo pigments.Contemplated azo pigments are in particular C.I. Pigment Yellow 1, 3,12, 13, 14, 16, 17, 65, 73, 74, 75, 81, 83, 97, 111, 120, 126, 127, 151,154, 155, 174, 175, 176, 180, 181, 183, 191, 194, 198; Pigment Orange 5,34, 36, 38, 62, 72, 74; Pigment Red 2, 3, 4, 8, 12, 14, 22, 48:1-4,49:1, 52:1-2, 53:1-3, 57:1, 60:1, 112, 137, 144, 146, 147, 170, 171,175, 176, 184, 185, 187, 188, 208, 214, 242, 247, 253, 256, 266; PigmentViolet 32; Pigment Brown 25.

[0056] With regard to dyes, disperse dyes are contemplated as well aswater-soluble anionic and cationic dyes. Contemplated dyes are inparticular mono-, dis- or polyazo dyes and also formazan oranthraquinone dyes. Water-soluble dyes are in particular the alkalimetal salts or ammonium salts of reactive dyes and also of acidic wooldyes or direct cotton dyes of the azo series. Contemplated azo dyes arepreferably metal-free and metallizable monoazo, disazo and trisazo dyescontaining one or more sulfonic acid or carboxylic acid groups, heavymetal-containing, namely copper-, chromium or cobalt-containing monoazo,disazo and trisazo dyes. The intermediates for the metal-containing dyesmay be prepared by the customary method in a conventional batch process.The subsequent metal complexing reaction, for example with copper ions,is then preferably carried out at temperatures between 30 and 100° C. ina microreactor.

[0057] Contemplated reactive azo dyes are in particular C.I. ReactiveYellow 15, 17, 37, 57, 160; Reactive Orange 107; Reactive Red 2, 23, 35,180; Reactive Violet 5; Reactive Blue 19, 28, 203, 220; and ReactiveBlack 5, 8, 31.

[0058] This process also provides in particular C.I. Acid Yellow 17, 23;Direct Yellow 17, 86, 98, 132, 157; and Direct Black 62, 168 and 171.

[0059] It is surprising and was unforeseeable that the production of azocolorants is possible in this technically elegant way, since it washitherto assumed that the production of solids in the microreactor wouldcause the system to clog up.

[0060] The azo pigments prepared according to the invention are usefulfor pigmenting macromolecular organic materials of natural or syntheticorigin, for example plastics, resins, coatings, paints orelectrophotographic toners and developers and also inks, includingprinting inks.

[0061] The azo dyes prepared according to the invention are useful fordyeing or printing hydroxyl-containing or nitrogenous natural organicand also synthetic substrates. Such substrates include for examplesynthetic or natural fiber materials and also leather materialscomprising predominantly natural or regenerated cellulose or natural orsynthetic polyamides. They are particularly useful for dyeing andprinting textile material based on acetate, polyester, polyamide,polyacrylonitrile, PVC and polyurethane fibers and also wool or inparticular cotton. To this end, the dyes can be applied to the textilematerials by the usual exhaust, padding or printing processes.

[0062] The azo colorants prepared according to the invention are usefulas colorants in electrophotographic toners and developers, for exampleone- or two-component powder toners (also known as one- or two-componentdevelopers), magnet toners, liquid toners, latex toners, polymerizationtoners and also specialty toners, such as microencapsulated toners,based for example on wax, CD/DVD-dyes.

[0063] Typical toner binders are addition polymerization, polyadditionand polycondensation resins, such as styrene, styrene-acrylate,styrene-butadiene, acrylate, polyester, phenol-epoxide resins,polysulfones, polyurethanes, individually or in combination, and alsopolyethylene and polypropylene, which may each include furtheringredients, such as charge control agents, waxes or flow assistants, orare subsequently modified with these additives.

[0064] In order to obtain electrophotographic toners or developershaving either a positive or a negative charge, it is common to addcharge control agents. As the coloring component in color toners, use istypically made of organic color pigments. As compared with dyes, colorpigments have considerable advantages on account of their insolubilityin the application medium, such as improved thermal stability andlightfastness, for example.

[0065] On the basis of the principle of subtractive color mixing it ispossible, with the aid of the three primary colors yellow, cyan andmagenta, to reproduce the entire spectrum of colors visible to the humaneye. Exact color reproduction is possible only if the particular primarycolor satisfies the precisely defined coloristic requirements. If it isnot the case, some shades cannot be reproduced, and the color contrastis inadequate.

[0066] In the case of full color toners, the three toners yellow, cyanand magenta must not only meet the precisely defined color requirementsbut must also be matched exactly to one another in terms of theirtriboelectric properties, since they are transferred one after the otherin the same device.

[0067] 6- and 7-color systems are likewise known. The base colors arered, green, blue, cyan, magenta, yellow, and black. It is also possibleto produce full color prints by the Pantone Hexachrome® system with thecolors cyan, magenta, yellow, black, orange and green.

[0068] It is known that colorants may have a long-term effect on thetriboelectric charging of toners. As a result, it is normally notpossible simply to add the colorants to a toner base formulation onceprepared. It may instead be necessary to prepare a specific formulationfor each colorant, with the nature and amount of the required chargecontrol agent being tailored specifically. This approach is,correspondingly, laborious and in the case of color toners for processcolor is just another difficulty to add to those already describedabove.

[0069] Furthermore, it is important for practical use that the colorantspossess high thermal stability and good dispersibility. Typicaltemperatures for incorporation of colorants into the toner resins arebetween 100° C. and 200° C. when using compounders or extruders.Accordingly, a thermal stability of 200° C., or better still 250° C., isof great advantage. It is also important that the thermal stability ismaintained over a prolonged period (about 30 minutes) and in differentbinder systems.

[0070] Besides the physical effect of the toner constituents withrespect to coloristics and electrostatics, and an optimum dispersibilityof the components, the quality of the toners is critically influenced bythe preparation process of the colorant. Of major importance arecolorants, especially pigments, having high color strength and hightransparency.

[0071] The azo colorants prepared according to the invention are furtheruseful as colorants in powders and powder coatings, especially intriboelectrically or electrokinetically sprayable powder coatings usedfor surface coating of objects composed for example of metal, wood,plastic, glass, ceramic, concrete, textile material, paper or rubber.

[0072] Powder coating resins used are typically epoxy resins, carboxyl-and hydroxyl-containing polyester resins, polyurethane and acrylicresins together with customary hardeners. Combinations of resins arealso used. For instance, epoxy resins are frequently used in combinationwith carboxyl- and hydroxyl-containing polyester resins. Typicalhardener components (depending on the resin system) include for exampleacid anhydride, imidazoles and also dicyandiamide and derivativesthereof, capped isocyanates, bisacylurethanes, phenolic and melamineresins, triglycidyl isocyanurates, oxazolines and dicarboxylic acids.

[0073] The azo colorants prepared according to the invention are alsouseful as colorants in inks, preferably inkjet inks, for example on anaqueous or nonaqueous basis, microemulsion inks and also in such inks asoperate according to the hot-melt principle.

[0074] Inkjet inks generally include a total of 0.5 to 15% by weight,preferably 1.5 to 8% by weight, (reckoned dry) of one or more of thecompounds according to the invention. Microemulsion inks are based onorganic solvents and water with or without an additional hydrotropicsubstance (interface mediator). Microemulsion inks include 0.5 to 15% byweight, preferably 1.5 to 8% by weight, of one or more of the compoundsaccording to the invention, 5 to 99% by weight of water and 0.5 to 94.5%by weight of organic solvent and/or hydrotropic compound.

[0075] Solvent based inkjet inks preferably include 0.5 to 15% by weightof one or more compounds according to the invention, 85 to 99.5% byweight of organic solvent and/or hydrotropic compounds.

[0076] Hot-melt inks are based mostly on waxes, fatty acids, fattyalcohols or sulfonamides that are solid at room temperature and liquefyon heating, the preferred melting range lying between about 60° C. andabout 140° C. Hot-melt inkjet inks consist essentially for example of 20to 90% by weight of wax and 1 to 10% by weight of one or more of thecompounds according to the invention. They may further include 0 to 20%by weight of an additional polymer (as “dye solvent”), 0 to 5% by weightof dispersant, 0 to 20% by weight of viscosity modifier, 0 to 20% byweight of plasticizer, 0 to 10% by weight of tack additive, 0 to 10% byweight of transparency stabilizer (prevents crystallization of waxes,for example) and also 0 to 2% by weight of antioxidant. Typicaladditives and assistants are described for example in U.S. Pat. No.5,560,760.

[0077] The azo colorants prepared according to the invention are alsouseful as colorants for color filters and also for additive as well assubtractive color generation and as colorants in electronic papers.

[0078] The present invention provides for a method of using an azocolorant, which has been prepared in a microreactor, as a colorant in anelectrophotographic toner or developer, powder coating, ink jet ink orelectronic medias, comprising incorporating said azo colorant into theelectrophotographic toner or developer, powder coating, ink jet ink baseor electronic medias.

[0079] The present invention further provides for an electrophotographictoner or developer, or a powder coating comprising a toner binder or apowder coating resin, and from 0.1 to 60% by weight, preferably 0.5 to20% by weight, of an azo colorant prepared in a microreactor.

[0080] The present invention further provides for an ink jet inkcomprising 0.5 to 15% by weight, preferably 1.5 to 8% by weight,(reckoned dry) of an azo colorant prepared in a microreactor.

[0081] The electrophotographic toners or developers, powder coatings,ink jet inks and electronic medias according to the present inventionare distinguished from those containing conventionally prepared azocolorants by significantly higher color strength and transparency.Although the particle size and shape of said azo colorants differ fromconventionally prepared azo colorants, the electrostatic properties,such as q/m values, of electrophotographic toners or developerscontaining said azo colorants are essentially alike. Therefore,surprisingly, transparency can simply be adjusted by blending an azocolorant prepared in a microreactor with an adequate amount of aconventionally prepared azo colorant of the same chemical structure,without influencing the electrostatic properties of the toner.

[0082] The azo pigments used in accordance with the invention may becombined with charge control agents providing either positive ornegative control, in order to achieve a particular charging behavior.The use of positive and negative charge control agents simultaneously isa further option. The charge control agents and the pigment granules maybe incorporated separately into the binder.

[0083] Examples of suitable charge control agents are:triphenylmethanes; ammonium and immonium compounds; iminium compounds;fluorinated ammonium and fluorinated immonium compounds; biscationicacid amides; polymeric ammonium compounds; diallylammonium compounds;aryl sulfide derivatives; phenol derivatives; phosphonium compounds andfluorinated phosphonium compounds; calix(n)arenes; resorcinols;cyclically linked oligosaccharides (cyclodextrins) and theirderivatives, especially boron ester derivatives, interpolyelectrolytecomplexes (IPECs); polyester salts; salt-like structured silicates,metal complex compounds, especially carboxylate-metal, salicylate-metaland salicylate-nonmetal complexes, aluminum azo complexes,α-hydroxycarboxylic acid-metal and -nonmetal complexes; boron complexesof 1,2-dihydroxyaromatics, 1,2-dihydroxyaliphatics or2-hydroxy-1-carboxyaromatics; benzimidazolones; azines, thiazines oroxazines which are listed in the Colour Index as Pigments, Solvent Dyes,Basic Dyes or Acid Dyes.

[0084] Examples of charge control agents are e.g. described inUS-2002-00 98 435-A1.

[0085] In a further embodiment, the present azo pigments can be combinedwith a wax during coupling, during finish, or afterwards as parts of amulti-component toner blend to provide electrophotographic toners ordevelopers. A specific wax-coating of pigment particles is described inUS-2002-00 98 435-A1.

[0086] For preparing a toner or developer, powder coating or ink jetink, the azo colorant of the present invention can be employed as a drypowder, an aqueous or non-aqueous dispersion, or a presscake, e.g. aflush paste.

[0087] For shading the hue of the present color toner, it is possible tocombine the azo colorant with an organic or inorganic pigment ofdifferent color (shade). It is also possible to combine the presentcolor toner with another color toner of different color (shade).

EXAMPLES

[0088] Percentages are by weight in the examples, hereinbelow.

Example 1 C.I. Pigment Red 2

[0089] Preparation of a Diazonium Salt Solution:

[0090] A 500 ml three-neck flask is charged with 14.6 g of solid2,5-dichloroaniline in 25.1 ml of water, and 30.8 ml of 31% hydrochloricacid are added. The mixture is stirred at RT for 8 hours to provide ahydrochloride solution. On addition of a further 25.1 ml of water and3.75 ml of 60% acetic acid the reaction mixture is cooled to −5° C. Atthis temperature, 11.5 ml of 40% sodium nitrite solution are addeddropwise to the reaction mixture over about 15 min and stirred in at 0°C. for a further 60 min. The reaction mixture is clarified by adding sixspatula tipfuls of Celite and rapidly filtering with suction. Theyellowish diazonium salt solution is made up with water tc a totalvolume of 300 ml (˜0.3 M).

[0091] Preparation of a Solution of the Coupling Component:

[0092] A second flask is charged with 23.9 g of Naphtol AS in 50.2 ml ofwater, and 26.7 ml of 25% aqueous sodium hydroxide solution are added.This mixture is then stirred at 60° C. for 120 min to dissolve it. It israpidly filtered with suction and likewise made up with water to a totalvolume of 300 ml (˜0.3 M).

[0093] Azo Coupling in Microreactor

[0094] The conventionally prepared diazonium salt and Naphtol solutionsare pumped via calibrated piston pumps into the respective reactantinlets of the microreactor at a flow rate of 6 ml/min in each case. Theactual azo coupling takes place in the reactor space. To obtain abuffering effect, these reactant solutions are diluted with an aceticacid solution (4 ml of 60% acetic acid and 600 ml of water) shortlyupstream of the reactor inlets. The acetic acid solution is likewise fedat a flow rate of 6 ml/min into the reactant feed lines of themicroreactor via a T-junction by means of calibrated piston pumps. Theheat exchanger circuit of the microreactor is connected to a thermostatwhich ensures a reaction temperature of 40° C. At the reactor outlet theproduct suspension pH is about 3. The product suspension emerging fromthe reactor is collected in a flask, filtered off with suction andwashed neutral with water. The moist C.I. Pigment Red 2 is dried at 65°C.

Example 2

[0095] Preparation of a Hydrochloride Solution of 2,5-dichloroaniline

[0096] A 500 ml three-neck flask is charged with 14.6 g of solid2,5-dichloroaniline in 25.1 ml of water, 30.8 ml of 31% hydrochloricacid are added and the batch is stirred at room temperature for 8 hours.A further 25.1 ml of water and 3.75 ml of 60% acetic acid are added, andthe solution is cooled to −5° C.

[0097] Solution of Naphtol AS

[0098] A flask is charged with 23.9 g of Naphtol AS in 50.2 ml of water,and 26.7 ml of 25% aqueous sodium hydroxide solution are added. Thismixture is then stirred at 60° C. for 120 min to dissolve it. It israpidly filtered with suction and likewise made up with water to a totalvolume of 300 ml (˜0.3 M).

[0099] Dilute Sodium Nitrite Solution

[0100] A 1 N aqueous sodium nitrite solution is prepared.

[0101] Buffer Solution

[0102] A buffer solution is prepared from 4 ml of 60% acetic acid and600 ml of water.

[0103] Diazotization of 2,5-dichloroaniline in Microreactor

[0104] The 2,5-dichloroaniline hydrochloride solution prepared under a)is adjusted to 100 ml. The reactant solution and the 1N sodium nitritesolution from c) are pumped via calibrated piston pumps into therespective reactant inlets of the microreactor at a flow rate of 12ml/min each. The diazotization reaction takes place in the reactorspace. The heat exchanger circuit of the microreactor is connected to athermostat which ensures the desired reaction temperature of about 5° C.The reaction solution emerging from the reactor is bulked with water to300 ml in a collecting vessel and any excess sodium nitrite present isdestroyed with sulfamic acid. The diazonium salt solution (˜0.3 M) isused for azo coupling either in a downstream microreactor or in areaction vessel according to conventional processes.

[0105] Azo Coupling to form C.I. Pigment Red 2 in Microreactor

[0106] The diazonium salt solution prepared by diazotization in amicroreactor and also the Naphtol AS solution from b) are pumped viacalibrated piston pumps into the respective reactant inlets of themicroreactor at a flow rate of 6 ml/min each. The actual azo couplingtakes place in the reactor space mentioned. To obtain a bufferingeffect, these reactant solutions are diluted with an acetic acid bufferprepared according to d), shortly upstream of the reactor inlets. Thebuffer solution is likewise fed with the aid of calibrated piston pumpsinto the reactant feed lines of the microreactor at a flow rate of 6ml/min via a T-junction. The heat exchanger circuit of the microreactoris connected to a thermostat which ensures the desired reactiontemperature of about 40° C. The product suspension pH at the reactoroutlet is about 3. The product suspension emerging from the reactor iscollected in a piston, filtered off with suction and washed neutral withwater. The moist pigment is dried at 65° C.

Example 3 C.I. Pigment Yellow 191

[0107] Preparation of a Suspension of 2B-acid Hydrochloride

[0108] A 500 ml three-neck flask is charged with 46.2 g of solid 2B-acid(95.6%) (5-amino-3-chloro-2-methylbenzenesulfonic acid) in 400 ml ofwater, and 18.1 ml of 33% aqueous sodium hydroxide solution are added.The mixture is then heated to 90° C. After addition of 1.6 g of Celiteand further stirring at 90° C., the batch is filtered hot. 92.8 ml of20% hydrochloric acid are added to the filtrate to precipitate the aminehydrochloride.

[0109] Conventional Diazotization

[0110] The 2B-acid hydrochloride suspension is diazotized with 26.6 mlof 40% sodium nitrite solution at 20° C. Initially the nitrite ismetered in rapidly, while the rest is added at such a rate that there isalways a small detectable nitrite excess. The ready-produced diazoniumsalt suspension is adjusted with water to a total volume of 1 500 ml(about 0.13 molar).

[0111] Diazotization of 2B-acid in Microreactor

[0112] The 2B-acid hydrochloride suspension prepared according to a) isadjusted to 1 000 ml. The suspension and 40% of sodium nitrite solutionare pumped via calibrated piston pumps into the respective reactantinlets of the microreactor at a flow rate of 40 ml/min and 1 ml/minrespectively. The diazotization reaction takes place in the reactorspace. The heat exchanger circuit of the microreactor is connected to athermostat which ensures the desired reaction temperature of about 20°C. The reaction solution emerging from the reactor is stirred in acollection vessel for one hour in the presence of a small excess ofnitrite. Water is added to a total volume of 1 500 ml, and any excesssodium nitrite present is destroyed with sulfamic acid. The diazoniumsalt solution (˜0.13 M) is used for azo coupling either in a downstreammicroreactor or in a reaction vessel according to conventionalprocesses.

[0113] Solution of Pyrazole Acid Three(3-(3-methyl-5-oxo-4,5-dihydropyrazol-1-yl)benzenesulfonic Acid)

[0114] A flask is charged with 400 ml of water, and 57.7 g of pyrazoleacid three are added. 22.2 ml of 33% aqueous sodium hydroxide solutionare added to dissolve the acid. For coupling, the batch is adjusted withwater to a total volume of 750 ml or 0.26 M and heated to 40° C.

[0115] Azo Coupling in Microreactor

[0116] The diazonium suspension prepared under b) or c) and the pyrazoleacid three solution d) are pumped via calibrated piston pumps into therespective reactant inlets of the microreactor at a flow rate of 20ml/min and 10 ml/min respectively. The actual azo coupling takes placein the reactor space mentioned. The reaction is then carried out at areaction temperature of 40° C. and a pH of 6.3. The pigment suspensionis subsequently stirred at 40° C. for 60 min. It is then heated to 80°C. and maintained at 80° C. for 15 min. A solution of 1.7 mol of CaCl₂,61 mol of water, 0.0075 mol of sodium hydroxide and 0.01 mol of stearicacid is prepared per mole of pigment and added to the pigmentsuspension. The batch is stirred at 80° C. for 2 hours, then allowed tocool down to 70° C. and washed with water.

[0117] Laking to form Pigment Yellow 191 in Microreactor

[0118] The pigment suspension is made up to 2 500 ml, heated to 80° C.and maintained at 80° C. for 15 min with stirring. 33.4 g of 77% calciumchloride are dissolved in 250 ml of water in a 400 ml beaker.

[0119] The pigment suspension and the calcium chloride solution arepumped via calibrated piston pumps into the respective reactant inletsof the microreactor at a flow rate of 90 ml/min and 9 ml/minrespectively. The thermostat of the heat exchanger circuit of themicroreactor is set to a reaction temperature of 85° C. The pigmentsuspension emerging from the reactor is collected in a stock reservoirvessel. TABLE 1 Characterization of P.Y. 191 (conventional sample) andP.Y. 191 (microreactor sample): Parameter: Conventional SampleMicroreactor Sample 1) Charging q/m: in μC/g: 5 min −16 −15 10 min −16−15 30 min −16 −15 2 h −15 −15 24 h −11 −12 2) pH 6.3 7.4 3)Conductivity 0.19 mS/cm 0.33 mS/cm 4) Degradation >360° C. >360° C.(DTA) 5) Coloristic properties: Transparency Standard 6 more transparentBrightness Standard 5 brighter Cleanliness of shade Standard 3 clearerColor strength 100% 162% Hue Standard 6 greener

Example 4 C.I. Pigment Red 53:1

[0120] Preparation of a suspension of CLT-acid hydrochloride(2-amino-5-chloro-4-methylbenzenesulfonic acid)

[0121] A 500 ml three-neck flask is charged with 44.6 g of solidCLT-acid (99%) in 250 ml of water, and 31 ml of 31% hydrochloric acidare added. The mixture is stirred for 30 min.

[0122] Conventional Diazotization

[0123] The CLT-acid hydrochloride suspension is diazotized with 26.6 mlof 40% sodium nitrite solution at 20° C. Initially the nitrite ismetered in rapidly, the rest is added at such a rate that a small excessof nitrite is always detectable. The ready-prepared diazonium saltsuspension is adjusted with water to a total volume of 1 500 ml (0.13M).

[0124] Diazotization of CLT-acid in Microreactor

[0125] The CLT-acid hydrochloride suspension prepared under a) isadjusted to 1 000 ml. The suspension and a 40% sodium nitrite solutionare pumped via calibrated piston pumps into the respective reactantinlets of the microreactor at a flow rate of 40 ml/min and a flow rateof 1 ml/min respectively. The diazotization reaction takes place in thereactor space. The heat exchanger circuit of the microreactor isconnected to a thermostat which shows the desired reaction temperatureof about 15° C. The reaction solution emerging from the reactor iswarmed to 20° C. with a small excess of nitrite. After a delay time of60 min, it is made up with water to 1 500 ml and any excess sodiumnitrite present is destroyed with sulfamic acid. The diazonium saltsolution (˜0.13 M) is used for azo coupling either in a downstreammicroreactor or in a reaction vessel according to conventionalprocesses.

[0126] Solution of β-naphthol

[0127] A flask is charged with 400 ml of water, and 28.1 g of β-naphtholare added. 24.2 ml of 33% strength aqueous sodium hydroxide solution areadded to dissolve the naphthol. For coupling, the batch is adjusted withwater to a total volume of 750 ml or 0.26 M and heated to 40° C.

[0128] Azo Coupling in Microreactor

[0129] The diazonium suspension prepared under b) or c) and theβ-naphthol solution d) are pumped via calibrated piston pumps into therespective reactant inlets of the microreactor at a flow rate of 20ml/min and of 10 ml/min respectively. The actual azo coupling takesplace in the reactor space mentioned. The reaction is carried out at areaction temperature of 40 to 50° C. at a pH of 7.5. The pigmentsuspension is subsequently stirred at 40° C. and pH 7.5 for 30 min.

[0130] The pigment yield can be increased from 96% to 99% by thefollowing variation: the pigment suspension is adjusted to pH 2.0 with33% hydrochloric acid in a collecting vessel. After a delay time ofabout 10-15 min in the collecting vessel, the pigment suspension ispumped into a further microreactor. Sufficient 10% aqueous sodiumhydroxide solution is pumped in through the second reactant inlet that,after mixing in the reactor, a pH of 7.5 is obtained at the outlet. Thesubsequent procedure is as described above, ie. stirring at 40° C. andpH 7.5 for 30 min.

[0131] Laking to form Pigment Red 53:1 in Microreactor

[0132] The pigment suspension is made up to 2 500 ml, heated to 80° C.and maintained at 80° C. for 15 min with stirring.

[0133] 29 g of barium chloride×2H₂O are dissolved in 250 ml of water ina 400 ml beaker.

[0134] The pigment suspension and the barium chloride solution arepumped via calibrated piston pumps into the respective reactant inletsof the microreactor at a flow rate of 90 ml/min and 9 ml/minrespectively. The thermostat of the heat exchanger circuit of themicroreactor is set to a reaction temperature of 85-95° C. The pigmentsuspension emerging from the reactor is collected in a stock reservoirvessel.

Example 5 Water-Soluble Reactive Dyes

[0135] Reactive Orange 107

[0136] Diazotization of Para Base Ester (Conventionally)

[0137] 1.) Diazotization of para base ester(2-(4-aminobenzenesulfonyl)ethyl sulfate)

[0138] 25.5 g of 2-(4-aminobenzenesulfonyl)ethyl sulfate are introducedinto 200 g of water with stirring in a 500 ml beaker. 36 g of 31%hydrochloric acid are added dropwise and stirred in for 30 min. Thesuspension is cooled down to 0 to −5° C. About 20 g of 5N sodium nitritesolution are added dropwise at that temperature over 30 min. The batchis subsequently stirred at about 5° C. for 1-2 hours. Excess nitrite isdestroyed with sulfamic acid. The batch is made up with water to 300 ml(0.3 M).

[0139] Solution of 4-acetylamino-2-aminobenzenesulfonic Acid

[0140] 21 g of 4-acetylamino-2-aminobenzenesulfonic acid are added to250 g of water and adjusted to pH 4.3 with solid sodium bicarbonate. Thesolution is filtered with suction, made up to a volume of 300 ml withwater (˜0.3 M) and heated to 50° C.

[0141] Buffer Solution

[0142] A buffer solution is prepared from 75 g of acetic acid (100%) and66 g of sodium acetate (anhydrous) in 800 g of water.

[0143] Azo Coupling in Microreactor

[0144] The diazonium component suspension prepared conventionally underal) and the solution of 4-acetylamino-2-aminobenzenesulfonic acid a2)are pumped via calibrated piston pumps into the respective reactantinlets of the microreactor at a flow rate of 6 ml/min in each case. Theactual azo coupling takes place in the reactor space mentioned. Toobtain the pH of 4-4.5 required for the azo coupling, these reactantsolutions are diluted with an acetic acid/sodium acetate buffer preparedaccording to a3), shortly upstream of the reactor inlets. The buffersolution is likewise fed into the reactant feed lines of themicroreactor using calibrated piston pumps at a flow rate of 6 ml/minvia a T-junction. The heat exchanger circuit of the microreactor isconnected to a thermostat which shows the desired reaction temperatureof 50° C. The product suspension pH is between 3.8-4.5 at the reactoroutlet. The dye solution emerging from the reactor is collected in aflask, adjusted to a pH of 5.5-6.0 with sodium bicarbonate andclarified. The reactive azo dye is isolated by evaporating or spraydrying.

1) A method of using an azo colorant, which has been prepared in amicroreactor, as a colorant in an electrophotographic toner ordeveloper, powder coating, ink jet ink or electronic medias, comprisingthe step of incorporating the azo colorant into the electrophotographictoner or developer, powder coating or ink jet ink base or electronicmedias. 2) The method as claimed in claim 1, wherein the azo colorant isan azo pigment. 3) The method as claimed in claim 1, wherein the azopigment is C.I. Pigment Yellow 1, 3, 12, 13, 14, 16, 17, 65, 73, 74, 75,81, 83, 97, 111, 120, 126, 127, 151, 154, 155, 174, 175, 176, 180, 181,183, 191, 194, 198; Pigment Orange 5, 34, 36, 38, 62, 72, 74; PigmentRed 2, 3, 4, 8, 12, 14, 22, 48:1-4, 49:1, 52:1-2, 53:1-3, 57:1, 60:1,112, 137, 144, 146, 147, 170, 171, 175, 176, 184, 185, 187, 188, 208,214, 242, 247, 253, 256, 266; Pigment Violet 32; or Pigment Brown
 25. 4)A process for preparing a colored electrophotographic toner ordeveloper, powder coating or ink jet ink, comprising the steps ofconducting one or more of a) diazotization of aromatic or hetaromaticamines, b) azo coupling, c) laking and d) metal complexing in amicroreactor to give an azo colorant, and incorporating the azo colorantinto the electrophotographic toner or developer, powder coating or inkjet ink base. 5) The process as claimed in claim 4, wherein thediazotization, or the azo coupling, or the laking, or the diazotizationand the azo coupling, or the diazotization and the azo coupling and thelaking, are carried out in a microreactor. 6) The process as claimed inclaim 4, wherein the diazotization or the azo coupling reaction, or themetal complexing reaction, or the diazotization and the azo couplingreaction, or the diazotization and the azo coupling reaction and themetal complexing reaction, are carried out in a microreactor. 7) Theprocess as claimed in claim 4, wherein the diazotization and subsequentazo coupling are conducted using two or more microreactors connected inseries or microreactors having two or more reaction zones. 8) Theprocess as claimed in claim 4, wherein a solution or suspension of acoupleable diazonium salt and a solution or suspension of an azocoupling component are continuously introduced into the microreactor,continuously mixed with each other in the microreactor and reacted. 9)The process as claimed in claim 4, wherein a solution or suspension ofaromatic or hetaromatic amine or its ammonium salt and a solution orsuspension of a diazotizing agent are continuously introduced into themicroreactor, continuously mixed with each other in the microreactor andreacted. 10) The process as claimed in claim 4, wherein a solution orsuspension of an azo colorant that contains acid groups and a solutionor suspension of a metal salt are continuously introduced into themicroreactor, continuously mixed with each other in the microreactor andreacted. 11) The process as claimed in claim 4, wherein the azo colorantis an azo pigment. 12) The process as claimed in claim 11, wherein theazo pigment is C.I. Pigment Yellow 1, 3, 12, 13, 14, 16, 17, 65, 73, 74,75, 81, 83, 97, 111, 120, 126, 127, 151, 154, 155, 174, 175, 176, 180,181, 183, 191, 194, 198; Pigment Orange 5, 34, 36, 38, 62, 72, 74;Pigment Red 2, 3, 4, 8, 12, 14, 22, 48:1-4, 49:1, 52:1-2, 53:1-3, 57:1,60:1, 112, 137, 144, 146, 147, 170, 171, 175, 176, 184, 185, 187, 188,208, 214, 242, 247, 253, 256, 266; Pigment Violet 32; Pigment Brown 25.13) The process as claimed in claim 12, wherein the azo pigment is C.I.Pigment Yellow
 191. 14) The process as claimed in claim 4, furthercomprising the step of incorporating a charge control agent into theelectrophotographic toner or developer or powder coating. 15) Theprocess as claimed in claim 14, wherein the charge control agent isselected from the group consisting of triphenylmethanes, ammonium andimmonium compounds; iminium compounds; fluorinated ammonium andfluorinated immonium compounds; biscationic acid amides; polymericammonium compounds; diallylammonium compounds; aryl sulfide derivatives;phenol derivatives; phosphonium compounds and fluorinated phosphoniumcompounds; calix(n)arenes; resorcinols; cyclically linkedoligosaccharides (cyclodextrins) and their derivatives, especially boronester derivatives, interpolyelectrolyte complexes (IPECs); polyestersalts; salt-like structured silicates, metal complex compounds,especially carboxylate-metal, salicylate-metal and salicylate-nonmetalcomplexes, aluminum azo complexes, α-hydroxycarboxylic acid-metal and-nonmetal complexes; boron complexes of 1,2-dihydroxyaromatics,1,2-dihydroxyaliphatics or 2-hydroxy-1-carboxyaromatics;benzimidazolones; azines, thiazines and oxazines. 16) The process asclaimed in claim 11, wherein the azo pigment is coated with a wax. 17)The process as claimed in claim 4, further comprising the step ofincorporating an organic or inorganic pigment having a color differentthan the azo colorant into the electrophotographic toner or developer,powder coating or ink jet ink base. 18) An electrophotographic toner ordeveloper, or powder coating comprising a toner binder or a powdercoating resin, and from 0.1 to 60% by weight of an azo colorant preparedin a microreactor. 19) An ink jet ink comprising 0.5 to 15% by weight ofan azo colorant prepared in a microreactor. 20) A composition made inaccordance with the process of claim 4, wherein the composition isselected from the group consisting of an electrophotographic toner ordeveloper, powder coating and ink jet ink. 21) A process of preparing acomposition comprising the step of incorporating into the composition anazo colorant prepared in a microreactor, wherein the composition isselected from the group consisting of an electrophotographic toner ordeveloper, powder coating, ink jet ink and an electronic media.